Recently, in a field of biochemical test and genetic test, high detection sensitivity for an analyte has been required, and positioning of a fluorescent dye as a labeling agent (a labeling substance) has become a very important factor.
Among the fluorescent dyes, cyanine dye derivatives are commonly used as a dye having a fluorescence characteristics in a near-infrared region equal to or longer than 500 nm, and, for example, Cy3, Cy5 (produced by GE Healthcare Bioscience Co., Ltd. (former name: Amersham Bioscience Co. Ltd.) and the like are known as a leading fluorescent reagent.
Cy3 and Cy5 have a structure (indolenine-based cyanine dye) where two indolenine skeletons are bound to a polymethine chain, and by using this structure as a basic skeleton, various cyanine dye derivatives have been developed aiming at, for example, improvement of water-solubility, higher sensitivity by avoiding an aggregation state or the like (see, for example, Patent Literature 1, Patent Literature 2, Patent Literature 3, or the like). In addition, as other cyanine dye derivatives, there have been developed those having a structure where an azaindolenine skeleton and a pyrazole skeleton are bound to a polymethine chain (see, for example, Patent Literature 4, Patent Literature 5, or the like). Still further, there have been developed those having a structure where two indolenine skeletons bound to, for example, a polymethine chain or the like are further cross-linked with a spacer or the like (see, for example, Patent Literature 6, Patent Literature 7, Patent Literature 8, or the like).
In addition, as a fluorescent dye exhibiting higher sensitivity and higher water-solubility at a short wavelength region than the conventional optical systems, cyanine-based dye derivatives having a pyrazole skeleton and an indole skeleton have been developed (see Patent Literature 9).
On the other hand, a fluorescent dye can also be used as an internal standard substance in an electrophoresis. However, as for a fluorescent dye which has high fluorescence intensity and also controllable migration velocity, any satisfiable dye has not been obtained and further development has been desired.
Patent Literature 1: U.S. Pat. No. 5,268,486
Patent Literature 2: U.S. Pat. No. 5,486,616
Patent Literature 3: U.S. Pat. No. 5,569,766
Patent Literature 4: JP-A-2003-034696
Patent Literature 5: JP-A-2003-034697
Patent Literature 6: U.S. Pat. No. 5,571,388
Patent Literature 7: U.S. Pat. No. 5,800,995
Patent Literature 8: WO01/02374
Patent Literature 9: WO2007/114398